Crane



April 1963 R. L. BEVARD 3,083,838

CRANE Filed Aug. 15, 1962 4 Sheets-Sheet 1 INVENTOR.

Roger L. Beva rd Anornev R. L. BEVARD 'April 2, 1963 CRANE 4 Sheets-Sheet 2 Filed Aug. 15, 1962 INVENTOR Roger L. Bevard HW w.

Filed Aug- 15, 1963 as 4 she ts-$119 3 INVENTOR Roger L. Bevurd 6W4 MW Attorney FIG.5

R. L. BEVARD April 2, 1963 CRANE 4 Sheets-Sheet 4 Filed Aug. 15, 1962 INVENTOR Roger L. Bevord Attorney llnit rtes atent 3,083,838 CRANE Roger L. llevard, Iron Mountain, Mich, assignor to Lake Shore, Inc, iron Mountain, Mich, a corporation of l ichigan Filed Aug. 15, B62, Ser. No. 217,040 28 Qlaims. ((31. 212-74) This invention relates to cranes and, more particularly, to ship mounted cranes.

An object of this invention is to provide a crane having an increased reach while maintaining a compact stowed size and a relatively simplified construction.

Another object of this invention is to further provide such a crane including a load trolley of relatively simple and lightweight construction.

A further object of this invention is to provide a crane having telescoping booms and a load trolley arranged for joint and relative movement and wherein the vertical position of the load engaging mechanism of the crane does not change while the boom and trolley move horizontally.

Still another object of this invention is to limit the travel of the load engaging means; and, further, to do so without materially adding to the complexity of the crane on the load trolley.

For the achievement of these and other objects of this invention, it is proposed to provide a crane including at least a pair of telescopically arranged booms so interconnected that driving one boom produces both joint and relative movement of the booms. Such an arrangement provides both a compact stowed size and an increase in reach for a given size boom. A load trolley is supported from and movable with one of the booms and is so interconnected with both booms that relative movement between the booms moves the load trolley relative to the boom from which it is supported. To further simplify the crane construction, the hoist mechanism is located exteriorly of the load trolley with the hoist cable being reeved on the booms and the trolley so that the vertical position of the load engaging portion of the hoist mechanism does not vary during horizontal movement between the booms and trolley. Preferably, the above described relative movement is accomplished through a simple arrangement in which constant lengths of cable are reeved between the relatively movable members. Thus, one length establishes a driving connection between the booms and another length establishes a driving connection between one of the booms and the trolley. With such an arrangement synchronized movement is provided between the three elements. In effect, the hoist cable is also a constant length of cable, except when paying out or taking in cable, supporting the load engaging hook so as to maintain the hook at a constant vertical height during boom and trolley movement.

Other objects and advantages will be pointed out in, or be apparent from, the specification and claims, as will obvious modifications of the single embodiment shown in the drawings, in which:

FIG. 1 is a schematic illustration of a typical installation;

FIG. 2 is a top plan view of the crane;

FIG. 3 is a partial bottom view of the crane;

MG. 4 is an enlarged view of a cable anchor;

FIG. 5 is a side elevation of the booms;

FIG. 6 is a partial section generally along line 6-6 of FIG. 2;

FIG. 7 is a schematic reeving diagram;

FIG. 8 is a side elevation of the load trolley;

FIG. 9 is a top plan view of the load trolley; and

FIG. 10 is a partial view of and FIG. 11 is a schematic lee illustration of an arrangement for limiting the upper travel of the load engaging mechanism.

With reference to the drawings, FIG. 1 shows the crane 16 supported from overhead frame 14 below decks of vessel 12. Crane 10 includes booms which are extendable through ports 16 and .18 located on either side of the ship. With this arrangement, cargo can be hoisted from dock 29 (or a lighter) hauled into the ship and lowered through hatches to any desired level for stowage. Although this invention is particularly well suited for use in the environment shown, it will be appreciated that its basic concept is applicable to any shipboard crane as well as to cranes used other than aboard ship.

More particularly, frame 14 includes athwart beams 22, 24, and 26. Beams 28, 30 and 31 are part of the ship structure and brackets 32 and 34 connect beams 22, 2 4 and 26 to beams 28, 3t) and 31 to complete connection of the frame to ship overhead 15. For convenience only a portion of frame 14 has been illustrated and it will be appreciated that the more than two brackets, 32 and 34, are normally provided.

A pair of booms 40 and 42 are telescopically arranged and supported from frame 14. Boom 40 comprises a pair of parallel T-shaped members 44 and 46 (see FIG. 6). Member 44 is made up of horizontal portions 48 and 5t interconnected by vertical portions 52 and 54 and member 46 is made up of horizontal portions 56 and 58 interconnected by vertical members 6i) and 62. The inner faces of members 48 and 50 are suitably machined to provide finished surfaces 64 and 65 and the inner faces of members 55 and 58 are also provided with finished surfaces 68 and 70. These finished surfaces provide guides to receive roller assemblies 36 and 38 supported from opposed sides of the fixed frame. Members 44 and 46 are interconnected by transversely extending horizontal braces 72, 74 and 76 to structurally complete boom 46 Thus, boom 40 is supported from and for movement relative to the frame by roller assemblies 36 and 38. Racks 80 and 32 are provided on elongated members 4-4 and 46 for engagement by pinions 84 and 86 carried on a shaft 88. Shaft 38 is connected to motor 78 by coupling 90 and a suitable gear box 91. Accordingly, rotation of shaft 88 causes boom 49 to move athwartship.

A limit switch 92 is connected to shaft 88 and is driven simultaneously with boom 40. The limit switch is connected in circuit with motor 78 to controlthe extent of travel of boom 40 and prevent undesirable overtravel. The structure of limit switch 92 is well known to those skilled in the art and therefore is not shown. Furthermore, suitable overtravel stops (not shown) can be provided between frame 14 and boom 40, if desired.

Boom 42 includes spaced parallel portions 94 and 96 each comprising stacked channel members 98, 100 and 102, 104 respectively. Portions 94 and 96 are connected by transversely extending braces 196 and each carries a plurality of roller assemblies 108 and 110. Roller assemblies 168 are engaged between a longitudinal flange 116 extending from vertical member 54 and a finished surface 118 of horizontal portion 59. A brace 120 extends between flange 116 and horizontal portion 48 to provide vertical reinforcement for the flange. Similarly, roller assemblies are engaged between a longitudinal flange 122 and finished surface 124 with a brace 126 providing vertical reinforcement for the flange. In this manner, boom 42 is supported from boom 40 for movement therewith and is also capable of moving relative to boom 40. For stowage boom 42 is withdrawn into boom 40 to align the ends of the booms so as to occupy a minimum of space and, as is well known in the art, suitable stowage pins (not shown) can be provided to lock the booms in stowed condition. As illustrated in FIG. 2, boom 40 has 3 been displaced to the left by the rack and pinion combination and it will be noted that boom 42 is partially extended for boom 48. This extension of boom 42 occurs as a result of relative movement between the boom 48 and the frame and through an arrangement to be described hereinafter.

A load trolley 138 is supported from inner boom '42 and includes a generally rectangular body 129 from which two pairs of rollers 132 and 134 are supported. The rollers engage lower flanges 136 and 138 of portions 190 and 104 so that the trolley is movable with and relative to inner boom 42. The arrangement for producing movement of the load trolley relative to boom 42 will be described more completely hereinafter. The load trolley also includes sheaves 13 9 and 148 rotatably supported from body 129 and load engaging mechanism 142 suspended between the sheaves by hoist cable 144. The load engaging mechanism preferably takes the form of a block including sheave 148 and hook 150.

Preferably, relative movement of the booms and load trolley is produced through a sheave and cable arrangement wherein constant lengths of cable interconnect the relatively movable members to provide synchronized movement therebetween and, in the case of the load engaging mechanism, to maintain hook 158 at a preselected vertical height during horizontal movement. In FIG. 3 the various cables are illustrated by dot-dash lines and in FIG. 7 the elements fixed relative to the booms, those movable with boom 40 and those movable with boom 42 -are designated by full shading, horizontal lines and vertical lines. More particularly, portions 44 and 46 of boom 44) carry sheaves 152, 154 and 156, 158 adjacent their opposed ends. Cable 168 is connected at one end to cable anchor 162 supported from fixed frame 14 and extends around sheave 154 to cable anchor 164 connected to the inner boom 42. Cable 166 also has its ends connected to anchors 162 and 164 and extends around sheave 152 located at the opposite end of portion 44. A similar arrangement is provided on the opposite side of boom 40 at portion 46, where cable 168 has its ends connected to cable anchors 170 and 172 and extends around sheave 158, and cable 174 extends around sheave 156 with its ends also connected to anchors 178 and 172. With this arrangement, movement of boom 40 relative to the frame is transmitted through the constant lengths of cable to boom 42 so that inner boom 42, in addition to moving with outer boom 40, also moves relative to the outer boom. In this manner, driving boom 46) relative to the frame also produces telescoping movement between the two booms.

Through a similar cable arrangement the relative movement of the booms is utilized to move the load trolley along the inner booms 42. More particularly, portions 94 and 96 of boom 42 carry sheaves 176, 178 and 180, 182, respectively, at their opposed ends. Cable 184 is connected at one end to a cable anchor 186 carried on portion 44 of outer booms 40, is reeved on sheave 176, threaded through cable guide 187 on the trolley, and passes over sheave 189 to anchor 188 carried on portion 46 of outer boom 40. At the opposite end of inner boom 42, cable 190 has its ends connected to anchors 186 and 188 and is reeved over sheaves 178 and 182 and is threaded through cable guide 194 on the trolley. Accordingly, constant lengths of cable interconnect the booms and the trolley so that relative movement between the booms, as described above, causes the trolley to travel on boom '42, this movement being in addition to the movement of the trolley with inner boom 42 relative to the outer boom.

With this cable reeving arrangement synchronized movement occurs between the booms and the trolley utilizing only a single drive source, motor 78. Taking for example a driven speed of 10 f.p.m. of boom 48 relative to the frame, the speeds of boom 42 and the trolley relative to'the frame'are 20 f.p.m. and 30 f.p.m. The driven speed of boom 46 can be selected as desired but the above relationship between its speed and that of the trolley and other boom remains the same.

For convenience the various cable anchors have been shown schematically and each preferably takes the form of that shown in FIG. 4, including spaced apart brackets 196 and 198 connected to a particular structural member, e.g. frame 14. Threaded studs 200 and 282 pass through the brackets and each includes a cable connection 204. Look nuts 206 and 288 hold the studs in position.

As shown in FIG. 2, the booms are in a partially extended position. Actuation of motor 78 moves the booms to the left or right, as desired, with relative movement of the booms causing boom 42 to telescope outwardly of boom 40 and the load trolley to move to the left on boom 42.

Block 142 is raised or lowered relative to load trolley through hoist mechanism 286, which includes hoist cable 144 wound on drum 208 which is in turn driven by motor 218. When the load engaging block is in a preselected position, with or without a load suspended from hook 150, motor 218 is tie-energized and drum 288 is locked in position with one end of cable 144 wound thereon. The opposite end of cable 144 is connected to cable anchor 212 on member 28 supporting frame 14. This provides a constant length of cable which is reeved through the relatively movable members, booms and trolley, in such a manner that the vertical position of block 142 does not vary as the booms and trolley move. More particularly, hoist cable sheaves 214, 216 and 228, 222 are carried at the opposed ends of booms 42 and 4 respectively, and cabie 144 extends from drum 288 through sheave 224 carried on frame 14, passes over sheave 229 on boom 40 and back to sheave 216 on boom 42. From sheave 216 the hoist cable is reeved over sheave on the load trolley, under sheave 148 of the block and over the other sheave 139 of the trolley. From the trolley the hoist cable passes over sheave 214 on boom 42 and from there over sheave 222 on boom 48 to anchor 212. Accordingly, block 142 is supported by a constant length of cable which is so reeved through the relatively movable members that cable 144 is simultaneously payed out and taken up by the booms and trolley, in accordance with their synchronized movement, to maintain a taut cable without vertical movement of the block. Furthermore, such an arrangement permits the hoist motor to be located remote from the load thereby permitting a relatively light and simply constructed trolley.

It will be noted that hoist cable 144 passes over a limit switch 226 which provides a slack line control. More particularly, the limit switch is included in the circuit of motor 218 and when the hoist cable goes slack is operative to de-energize the hoist motor and lock the hoist drum to prevent excessive cable pay out.

It will also be appreciated that suitable mechanical stops or electrical limit switches could be provided to limit the upward travel of the block and, correspondingly the load. An example of an arrangement for providing an upper limit on the travel of block 142 is illustrated in FIGS. 10 and 11 and includes electric limit switch 238 mounted on support frame 14. Actuating lever 232 of the switch is connected to one end of a messenger cable 234 and is reeved generally in a figure 8 on booms 48 and 42. More particularly, cable 234 is reeved over sheave 236 on boom 48, extends to and over sheave 238 on boom 42 and along boom 42 to sheave 248. From sheave 248 the messenger cable returns to boom 40 where it is reeved over sheave 242 with its opposite end being connected to anchor 244 on frame 14. Tension spring 246 is seated between frame 14 and lever 232 and normally holds the lever in an unactuated position, the full line position in FIG. 11.

Messenger cable 234 passes through load trolley 13%) where it is threaded through a number of rollers, or sheaves, 248, 25a and 252. Rollers 248 and 252 are supported in fixed relation on the load trolley and roller 250' is supported for movement relative to the trolley, for example by means of vertical slot 254 in body 129 which permits vertical movement of roller 25s, Roller 250 is positioned in the path of block 142 and if desired lever 256, pivoted from the load trolley, can be provided intermediate the block and roller 25%.

Messenger cable 234 is a constant length of cable anchored at its opposed ends on the frame and reeved over the telescoping booms so that movement of the booms and trolley relative to each other and the frame occurs without varying the tension on cable 234', i.e. neither causing slack cable nor increasing the tension on the cable. Therefore, when the block has been lowered from the trolley switch lever 232 is held in an unactuated position and roller 254 is in its down full line position. As the block is raised into the trolley, roller 25% is engaged and moved upwardly tending to shorten the figure 8 loop of cable 234, shortening the loop moves lever 232 to the right toward its dotted line position to actuate the switch and stop hoist motor 21% When the block is again lowered, spring 246 will return lever 232 to the full line position and roller 25% also returns to its full line position. It will be appreciated that the hoist line and sheaves of the trolley have been omitted for clarity and it will also be appreciated that rollers 248 and 252 could be included as part of sheaves 134 and 14% and roller 25H? could be directly engaged by block 142 if desired. Still other arrangements can be incorporated in the crane to limit the upper travel of the block, however, the arrangement shown is particularly advantageous since it places the electrical control apparatus at a point remote from the movable member of the crane so as to avoid the problem of running electric lines to the movable load trolley, or other movable elements, and does so while maintaining a compact, taut and sensitive control arrangement. However, the limit switch, or switches could be mounted on the load trolley for direct engagement by the block, with the electric lines being of constant length and reeved with the booms so as not to run slack or be unduly tenioned during boom and trolley movement.

Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims,

What I claim is:

1. Load handling apparatus comprising, in combination, a plurality of relatively movable booms, a load trolley supported from and movable relative to one of said booms and including load engaging means, means for driving one of said booms, means interconnecting said booms for producing relative movement therebetween in accordance with said driven movement, and means connecting said load engaging means in said load trolley for movement with and relative to said load trolley, said connecting means operative to compensate for said relative movement of said booms and said trolley to hold said load engaging means relatively stationary during said relative movement.

2. The combination of claim 1 wherein said booms are arranged in telescoping relationship.

3. Load handling apparatus comprising, in combination, a frame, a plurality of booms supported from said frame for movement relative to each other and said frame, a load trolley including load engaging means, means for supporting said load trolley from and for movement relative to one of said booms, means for driving one of said booms relative to said frame, means interconnecting said booms for transmitting said driven motion therebetween to produce relative movement between said booms in accordance with said driven movement of said one boom, means interconnecting both of said booms and said load trolley so that said relative movement of said booms is transmitted n 53 to and produces movement of said load trolley relative to said booms, means for moving said load engaging means relative to said trolley and including cable means adapted to have its ends fixed relative to said booms and said trolle and means supporting said cable means from said booms and said trolley so that said load engaging means remains stationary during relative movement of said booms and said trolley.

4. The combination of claim 3 wherein said booms are arranged in relative telescoping relationship.

5. Load handling apparatus comprising, in combination, a frame, a first elongated boom, means for moving said first boom relative to said frame, a second boom telescoped with and movable relative to said first boom, first constant length cable means connected between said frame and said second boom and supported by said first boom so that said second boom is moved in accordance with movement of said first boom, a load trolley supported for movement with and relative to said booms and including load engaging means, second constant length cable means engaging said load trolley and fixed to said first boom, means supporting said second cable means from said second boom so that relative movement between said first and second booms moves said load trolley relative tosaid second boom, hoist means for raising and lowering said load engaging means with respect to said load trolley and including a hoist cable adapted to be fixed at its opposite ends relative to said booms and said trolley, and means supporting said hoist cable from said booms and said trolley so that said load engaging means is held at a preselected height during relative movement of said booms and said trolley.

6. Load handling apparatus comprising, in combination, a plurality of relatively movable booms, a load trolley supported for movement with and relative to one of said booms, means for driving one of said booms, means interconnecting said booms for producing relative movement therebetween in accordance with said driven move: ment, and means connecting said load trolley to said booms and responsive to relative movement between said booms to drive said load trolley relative to said booms.

7. Load handling apparatus comprising, in combination, a frame, a plurality of relatively movable booms, means for driving one of said booms relative to said frame, a load trolley supported for movement with and relative to said booms, first constant length cable means connected between said frame and said booms and supported by said one boom so that movement of said one boom produces relative movement of said booms second constant length cable means engaging said load trolley, and means supporting said second length of cable from said booms so that relative movement between said booms moves said load trolley relative to said booms.

8. Load handling apparatus comprising, in combination, a frame, a plurality of relatively movable booms, sheave means carried at longitudinally spaced Points on each of said booms, means supporting one of said booms for movement relative to said frame, means for moving said one boom relative to said frame, first constant length cable means connected between said frame and said booms and reeved on the sheave means on said one boom so that movement of said one boom relative to said frame produces relative movement of said booms, a load trolley supported for movement with and relative to said booms, and second constant length cable feans engaging said lead trolley and reeved on the sheave means of said booms so that relative movement of said booms moves said trolley relative to said booms.

9. The combination of claim 8 wherein said booms are arranged in telescoping relationship.

0. Load handling apparatus comprising, in combination, a frame, a first elongated boom, sheave means carried at longitudinally spaced points on said first boom, means for supporting said first boom for movement relative to said frame, means for moving said first boom relaj tive to said frame, a second elongated boom arranged in telescoping relation with and movable relative to said first boom, sheave means carried at longitudinally paced points on said second boom, first constant lengths of cable connected between said frame and said second boom and reeved over said sheave means on said first boom so that said second boom moves in accordance with movement of and relative to said first boom, a load trolley, means supporting said trolley for movement relative to said second boom, second constant lengths of cable connected to said first boom and engaging said trolley, said second cables reeved over said sheave means on said second booms and arranged so that relative movement of said first and second booms moves said trolley relative to said second boom, and hoist means including load engaging means carried by said trolley and cable means, said hoist means operative to raise and lower said load engaging means relative to said trolley and the ends of said cable means adapted to be fixed relative to said booms and trolley, said cable means reeved over sheaves on said booms and said trolley so that said load engaging means is held at a preselected height during said relative movement of said booms and said trolley.

11. The combination of claim 10 including means sensitive to the movement of said load engaging means and controlling said hoist means in accordance with that movement, said hoist control means being operative to deenergize said hoist means when said load engaging means reaches a predetermined height to thereby limit the upper travel thereof.

12. Load handling apparatus comprising, in combination, a frame, a first elongated boom, sheave means carried at longitudinally spaced points on said first boom,

means for supporting said first boom for movement relative to said frame, means for moving said first boom relative to said frame, a second elongated boom arranged in telescoping relation with and movable relative to said first boom, sheave means carried at longitudinally spaced points on said second boom first constant lengths of cable connected between said frame and said second boom and reeved over said sheave means on said first boom so that said second boom moves in accordance with movement of and relative to said first boom, a load trolley, means supporting said load trolley for movement relative to said second boom, and second constant lengths of cable connected to. said first boom and engaging said load trolley, said second cables reeved over said sheave means on said second boom and arranged so that relative movement of said first and second booms moves said load trolley relative to said second boom.

13. Load handling apparatus comprising, in combination, a frame, a first elongated boom, sheave means disposed at longitudinally spaced points on said first boom, means supporting said first boom from and for movement relative to said frame, means for moving said first boom relative to said 'frame, a second elongated boom, sheave means disposed at longitudinally spaced points on said second boom, first cable means fixed to said frame and said second boom and reeved over said sheave means on said first boom so that said second boom moves in accordance with movement of and relative to said first boom, a load trolley, means supporting said load trolley from and for movement relative to said second boom, and second cable means fixed to said first boom and engaging said trolley, said second cable means reeved over said sheave means on said second boom so that relative movement of said first and second booms moves said trolley relative to said second boom.

14. Load handling apparatus comprising, in combination, a frame, a first elongated boom, sheave means disposed at longitudinally spaced points on said first boom, means supporting said first boom from and for movement relative to said frame, means for moving said first boom relative to said frame, a second elongated boom,'sheave means disposed at longitudinally spaced points on said second boom, first cable means fixed to said frame and said second boom and reeved over said sheave means on said first boom so that said second boom moves in accordance with movement of and relative to said first boom, a load trolley, means supporting said load trolley from and for movement relative to said second boom, second cable means fixed to said first boom and engaging said trolley, said second cable means reeved over said sheave means on said second boom so that relative movement of said first and second booms moves said trolley relative to said second boom, and hoist means including load engaging means carried by said trolley and a hoist cable, said hoist means operative to raise and lower said load engaging means relative to said trolley and the ends of said cable adapted to be fixed relative to said booms and said trolley, said hoist cable reeved over sheaves on said booms and said trolley so that said load engaging means is held at a preselected height during said relative movement of said booms and said trolley.

15. The combination of claim 14 including means sensitive to the movement of said load engaging means for controlling said hoist means and operative to limit upper travel of said load engaging means.

16. The combination of claimlS wherein said means for controlling said hoist means comprises control means including means positioned in the path of and arranged for engagement by said load engaging means during its upward travel so that said control means is actuated when said load engaging means reaches a predetermined height to limit the upward travel thereof.

17. The combination of claim 15 wherein said means for controlling said hoist means comprises a limit switch mounted in fixed relation to said first and second booms and said load trolley, means positioned in the path of and arranged for engagement with said load engaging means during upward travel thereof, and means connecting said last mentioned means to said limit switch for transmitting motion therebetween so that said limit switch is actuated when said load engaging means reaches a predetermined height to limit the upward travel thereof.

18. The combination of claim 17 wherein said connecting means comprises a third constant length of cable connected 'at one to said limit switch, at its opposite end to said frame, and supported on said booms to accommodate movement of said booms without varying the tension in said third length of cable.

19. The combination of claim 14 wherein said first and second booms are arranged in telescoping relationship with each other and said frame.

20. The combination of claim 19 including control means for said hoist means engaged by and sensitive to the tension in said hoist cable so that when said hoist cable goes slack said hoist means is de-energized.

21. In combination, a first boom supported on a ship for movement athwartship, means for driving said boom athwartship, a second boom carried by said first boom for movement with and with respect to said first boom, means responsive to movement of said first boom relative to said ship for moving said first and second booms relative to each other, a trolley carried by said second boom for movement with and with respect to said second boom, means responsive to said relative movement of said booms for moving said trolley with respect to said second boom, load engaging means carried by said trolley, a hoist drum mounted in a fixed location on said ship, and a hoist cable extending from said drum to said load engaging means and reeved over said booms and trolley so that its effective length remains unchanged during movement of said booms and trolley, whereby said load engaging means remains at the same elevation during said boom and trolley movement.

22. Load handling apparatus comprising, in combination, a fixed support member, at least one boom supported from and movable relative to said support member, a load trolley supported for movement with and relative to said boom, load engaging means on said load trolley, hoist means for raising and lowering said load engaging means, and means sensitive to the movement of said load engaging means and connected to and controlling said hoist means so that said hoist means is de energized when the travel of said load engaging means reaches a predetermined upper limit.

23. The combination of claim 22 wherein said hoist control means comprises means for selectively de-energizing said hoist means and including means positioned in the path of and arranged for engagement by said load engaging means during its upward travel so that said control means is actuated to de-energize said hoist means when said load engaging means reaches a predetermined height to limit the upward travel thereof.

24. Load handling apparatus comprising, in combination, a fixed support member, a first boom supported from and movable relative to said support member, a second boom supported for movement with and relative to said first boom, a load trolley supported from one of said booms for movement with and relative to said booms, load engaging means supported from said load trolley, hoist means for raising and lowering said load engaging means, and means sensitive to the movement of said load engaging means and connected to and controlling said hoist means so that said hoist means is deenergized when the travel of said load engaging means reaches a predetermined upper limit.

25. Load handling apparatus comprising, in combination, a fixed support member, a first boom supported from and movable relative to said support member, a second boom supported for movement with and relative to said first boom, a load trolley supported from one of said booms for movement with and relative to said booms,

load engaging means supported from said load trolley, hoist means for raising and lowering said load engaging means, control means connected to said hoist means and positioned in fixed relation to said booms and load trolley at a point remote therefrom, sensing means disposed in the path of said load engaging means and connected to said control means for actuating said control means in accordance with movement of said load engaging means to de-energize said hoist means when said load engaging means reaches a predetermined height.

26. The combination of claim 25 wherein said connecting means comprises a constant length of cable supported from said booms and said trolley.

27. The combination of claim 26 wherein said control means comprises an electric limit switch mounted on said fixed support member.

28. In combination, a first boom supported on a ship for movement athwartship, means for driving said boom athwartship, a second boom carried by said first boom for movement with and with respect to said first boom, means for moving said second boom relative to said first boom, a trolley carried by said second boom for movement with and with respect to said second boom, means for moving said trolley with respect to said second boom, load engaging means carried by said trolley, a hoist drum mounted in a fixed location on said ship, and a hoist cable extending from said drum to said load engaging means and reeved through said first and second booms so that its effective length remains unchanged during movement of said booms and trolley, whereby said lead engaging means remains at the same elevation during boom and trolley movement.

References Cited in the file of this patent UNITED STATES PATENTS 

1. LOAD HANDLING APPARATUS COMPRISING, IN COMBINATION, A PLURALITY OF RELATIVELY MOVABLE BOOMS, A LOAD TROLLEY SUPPORTED FROM AND MOVABLE RELATIVE TO ONE OF SAID BOOMS AND INCLUDING LOAD ENGAGING MEANS, MEANS FOR DRIVING ONE OF SAID BOOMS, MEANS INTERCONNECTING SAID BOOMS FOR PRODUCING RELATIVE MOVEMENT THEREBETWEEN IN ACCORDANCE WITH SAID DRIVEN MOVEMENT, AND MEANS CONNECTING SAID LOAD ENGAGING MEANS IN SAID LOAD TROLLEY FOR 